Optical disc apparatus

Abstract

One of the objects of the invention is to provide an optical disc apparatus capable of focusing on a signal surface regardless of appearance of a fake signal. The optical disc apparatus includes: an optical pickup for outputting a signal on the basis of reflection light of the optical disc, the optical pickup including an objective lens; a driving section for moving the objective lens of the optical pickup relative to an optical disc surface; and a focus controlling section for carrying out a focus detecting operation by detecting a reflection signal on a signal surface of the optical disc from the output signal of the optical pickup within a predetermined range of distance between the objective lens and the optical disc surface while the objective lens is being moved relative to the optical disc surface by means of the driving section.

1. An optical disc apparatus comprising:
 an optical pickup for outputting a signal on the basis of reflection light of the optical disc, the optical pickup including an objective lens; 
 a driving section for moving the objective lens of the optical pickup relatively to an optical disc surface; and 
 a focus controlling section for carrying out a focus detecting operation by detecting a reflection signal on a signal surface of the optical disc from the output signal of the optical pickup within a predetermined range of distance between the objective lens and the optical disc surface while the objective lens is being moved relative to the optical disc surface by means of the driving section, wherein 
 the driving section staffs to move the objective lens relative to the optical disc surface from a predetermined initial point at a substantially fixed speed, 
 the focus controlling section restricts the detection of the reflection signal on the signal surface of the optical disc until a predetermined time period has passed from a predetermined reference point of time after the start of the relative movement, and detects the reflection signal on the signal surface of the optical disc after the predetermined time period has passed to perform the focus detecting operation within the predetermined range of distance, and 
 the predetermined time period is determined based on a time period between a time when the signal due to the surface reflection on the surface of the optical disc is detected and a time when a fake signal due to the surface reflection on the surface of the optical disc is detected. 
 
   
   
     2. The optical disc apparatus according to  claim 1 , wherein the predetermined range of distance is at least a part of a range from the position of objective lens of optical pickup where the fake signal due to surface reflection on the optical disc is detected to the position of the surface of the optical disc. 
   
   
     3. The optical disc apparatus according to  claim 1 , wherein the focus controlling section performs a pre-search controlling operation for moving the objective lens relative to the optical disc surface within a predetermined range of pre-search distance by means of the driving section before the focus detecting operation and
 the predetermined range of distance is determined on the basis of the output signal of the optical pickup during the pre-search controlling operation. 
 
   
   
     4. The optical disc apparatus according to  claim 1 , wherein
 the focus controlling section performs a pre-search controlling operation for moving the objective lens relatively to the optical disc surface within a predetermined range of pre-search distance by means of the driving section before the focus detecting operation, 
 a parameter concerning the detection of the reflection signal on the signal surface is determined on the basis of the output signal of the optical pickup during the pre-search controlling operation and 
 the reflection signal on the signal surface of the optical disc is detected from the output signal of the optical pickup with the determined parameter within the predetermined range of distance between the objective lens and the optical disc surface in the focus detecting operation. 
 
   
   
     5. The optical disc apparatus according to  claim 1 , wherein
 the predetermined reference point of time is the point when the fake signal due to surface reflection on the optical disc is detected. 
 
   
   
     6. The optical disc apparatus according to  claim 1 , wherein
 the focus controlling section stops the focus detecting operation when a preset detection ending time has passed from the predetermined reference point of time after the start of the relative movement. 
 
   
   
     7. An optical disc apparatus, comprising:
 an optical pickup for outputting a signal on the basis of reflection light of the optical disc, the optical pickup including an objective lens; 
 a driving section for moving the objective lens of the optical pickup relative to an optical disc surface; and 
 a detection section for detecting a reflection signal on a signal surface of the optical disc from an output signal of the optical pickup within a predetermined range of time from a specified time while the objective lens is being moved relative to the optical disc surface by means of the driving section, wherein 
 the driving section staffs to move the objective lens relative to the optical disc surface from a predetermined initial point at a substantially fixed speed, 
 the detection section restricts the detection of the reflection signal on the signal surface of the optical disc until a predetermined time period has passed from a predetermined reference point of time after the staff of the relative movement, and detects the reflection signal on the signal surface of the optical disc after the predetermined time period has passed, and 
 the predetermined time period is determined based on a time period between a time when the signal due to the surface reflection on the surface of the optical disc is detected and a time when a fake signal due to the surface reflection on the surface of the optical disc is detected. 
 
   
   
     8. The optical disc apparatus according to  claim 7 , wherein
 the predetermined range of time is between the specified time and the time set before the objective lens of optical pickup reaches to the surface of the optical disc. 
 
   
   
     9. A method of controlling an optical disc apparatus including an optical pickup for outputting a signal on the basis of reflection light of the optical disc, the optical pickup including an objective lens, and a driving section for moving the objective lens of the optical pickup relative to an optical disc surface, wherein
 the objective lens is moved relative to the optical disc surface by means of the driving section while a reflection signal is detected on a signal surface of the optical disc from the output signal of the optical pickup within a predetermined range of distance between the objective lens and the optical disc surface, 
 the objective lens is moved by the driving section relative to the optical disc surface from a predetermined initial point at a substantially fixed speed, 
 the detection of the reflection signal on the signal surface of the optical disc is restricted until a predetermined time period has passed from a predetermined reference point of time after the start of the relative movement, and detects the reflection signal on the signal surface of the optical disc after the predetermined time period has passed, 
 the predetermined time period is determined based on a time period between a time when the signal due to the surface reflection on the surface of the optical disc is detected and a time when a fake signal due to the surface reflection on the surface of the optical disc is detected, and 
 a result of the detection of the reflection signal on the signal surface is used for setting a distance between the objective lens and the optical disc surface.